linux-kernel - Re: [PATCH v3] powerpc/pseries: detect secure and trusted boot state of the system.

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Date:   Fri, 17 Jul 2020 15:58:01 +1000
From:   Daniel Axtens <dja@...ens.net>
To:     Michal Suchánek <msuchanek@...e.de>,
        Nayna Jain <nayna@...ux.ibm.com>
Cc:     linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
        Mimi Zohar <zohar@...ux.ibm.com>
Subject: Re: [PATCH v3] powerpc/pseries: detect secure and trusted boot state of the system.

Michal Suchánek <msuchanek@...e.de> writes:

> On Wed, Jul 15, 2020 at 07:52:01AM -0400, Nayna Jain wrote:
>> The device-tree property to check secure and trusted boot state is
>> different for guests(pseries) compared to baremetal(powernv).
>> 
>> This patch updates the existing is_ppc_secureboot_enabled() and
>> is_ppc_trustedboot_enabled() functions to add support for pseries.
>> 
>> The secureboot and trustedboot state are exposed via device-tree property:
>> /proc/device-tree/ibm,secure-boot and /proc/device-tree/ibm,trusted-boot
>> 
>> The values of ibm,secure-boot under pseries are interpreted as:
>                                       ^^^
>> 
>> 0 - Disabled
>> 1 - Enabled in Log-only mode. This patch interprets this value as
>> disabled, since audit mode is currently not supported for Linux.
>> 2 - Enabled and enforced.
>> 3-9 - Enabled and enforcing; requirements are at the discretion of the
>> operating system.
>> 
>> The values of ibm,trusted-boot under pseries are interpreted as:
>                                        ^^^
> These two should be different I suppose?

I'm not quite sure what you mean? They'll be documented in a future
revision of the PAPR, once I get my act together and submit the
relevant internal paperwork.

Daniel
>
> Thanks
>
> Michal
>> 0 - Disabled
>> 1 - Enabled
>> 
>> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
>> Reviewed-by: Daniel Axtens <dja@...ens.net>
>> ---
>> v3:
>> * fixed double check. Thanks Daniel for noticing it.
>> * updated patch description.
>> 
>> v2:
>> * included Michael Ellerman's feedback.
>> * added Daniel Axtens's Reviewed-by.
>> 
>>  arch/powerpc/kernel/secure_boot.c | 19 +++++++++++++++++--
>>  1 file changed, 17 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
>> index 4b982324d368..118bcb5f79c4 100644
>> --- a/arch/powerpc/kernel/secure_boot.c
>> +++ b/arch/powerpc/kernel/secure_boot.c
>> @@ -6,6 +6,7 @@
>>  #include <linux/types.h>
>>  #include <linux/of.h>
>>  #include <asm/secure_boot.h>
>> +#include <asm/machdep.h>
>>  
>>  static struct device_node *get_ppc_fw_sb_node(void)
>>  {
>> @@ -23,12 +24,19 @@ bool is_ppc_secureboot_enabled(void)
>>  {
>>  	struct device_node *node;
>>  	bool enabled = false;
>> +	u32 secureboot;
>>  
>>  	node = get_ppc_fw_sb_node();
>>  	enabled = of_property_read_bool(node, "os-secureboot-enforcing");
>> -
>>  	of_node_put(node);
>>  
>> +	if (enabled)
>> +		goto out;
>> +
>> +	if (!of_property_read_u32(of_root, "ibm,secure-boot", &secureboot))
>> +		enabled = (secureboot > 1);
>> +
>> +out:
>>  	pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
>>  
>>  	return enabled;
>> @@ -38,12 +46,19 @@ bool is_ppc_trustedboot_enabled(void)
>>  {
>>  	struct device_node *node;
>>  	bool enabled = false;
>> +	u32 trustedboot;
>>  
>>  	node = get_ppc_fw_sb_node();
>>  	enabled = of_property_read_bool(node, "trusted-enabled");
>> -
>>  	of_node_put(node);
>>  
>> +	if (enabled)
>> +		goto out;
>> +
>> +	if (!of_property_read_u32(of_root, "ibm,trusted-boot", &trustedboot))
>> +		enabled = (trustedboot > 0);
>> +
>> +out:
>>  	pr_info("Trusted boot mode %s\n", enabled ? "enabled" : "disabled");
>>  
>>  	return enabled;
>> -- 
>> 2.26.2
>>